FFT Fourier code

From: james (attackack_at_yahoo.com)
Date: 01/14/05 

Date: 14 Jan 2005 02:48:50 -0800

Hallo

I'm trying to implemet the code about FFT or DFT but i can't
understand how is possible to calculate the real and the imaginary
parameter from a list of number that describe a waveform.
For example if i have a list of number like this and suppose a time
between data of one second:

0
10
20
30
20
10
0
-10
-20
...

now i need the real and the imaginary component from them to use FFT
of DFT function that is like this:

int DFT(int dir,int m,double *x1,double *y1)
{
...
}

where
double *x1 = real component
double *y1 = imaginary component

I've tryed to calculate these components but i get erroneous results.

Exist a code or similar that do it?

If you haven't this code can you tell me if you know some place in the
web where is possible to find this kind of code?

At this moment i've found only complicated mathematical formulas. Not
for me.

Thanks

Relevant Pages

  • Re: MATLABs FFT and fftshifting the input
    ... shifted, when N is even, MATLAB's fftshift puts the Nyquist ... and there is no Nyquist point for N odd. ... nonnegative frequency interval by the fft. ... just like the DFT except for a scaling factor. ...
    (comp.dsp)
  • Re: FFT Radix
    ... method of breaking-up an N-length FFT into two shorter length ones, ... Tukey algorithm. ... single step of decomposing of a size N = LM DFT into DFTs of size L ... it's obvious that one has no problem combining radix-2 and radix-4 ...
    (comp.dsp)
  • Re: Spectra of Unequally Sampled Data
    ... time samples the FFT requires. ... FFT of unequal spaced data ... FFT algorithm (of the DFT) is only applicable to evenly spaced ...
    (comp.soft-sys.matlab)
  • Re: Truncation error for Fourier transform?
    ... unbounded and continuous periodic time. ... is the DFT and its efficient version called the FFT. ... the only context i have ever heard of the FFT is as the DFT, ... conventional name for the series computed from a continuous function ...
    (comp.dsp)
  • Re: FFT Radix
    ... method of breaking-up an N-length FFT into two shorter length ones, ... lengths M & L. You calculate the length-N FFT using the following three ... Tukey algorithm. ... single step of decomposing of a size N = LM DFT into DFTs of size L ...
    (comp.dsp)